1. Technical Field
The present invention relates to an optical position detection device which optically detects the position of a target object, a light receiving unit suitable for use in the optical position detection device, and a display system with an input function including the optical position detection device.
2. Related Art
An optical position detection device has been proposed for optically detecting a target object. In the device, a plurality of point light sources are provided at positions separated from each other, and when detection light is emitted from each of the plurality of point light sources toward a target object through a light transmissive member, detection light reflected from the target object is transmitted through the light transmissive member and is then detected by a light receiving section (refer to JP-T-2003-534554). In addition, an optical position detection device has been proposed in which detection light emitted from each of a plurality of point light sources is emitted through a light guide plate and detection light reflected from a target object is detected by a light receiving section (refer to JP-A-2010-127671 and JP-A-2009-295318).
In this optical position detection device, a common light receiving section is used and the position of the target object is detected on the basis of a comparison result of the received light intensity in the light receiving section when some of the plurality of point light sources are turned on and the received light intensity in the light receiving section when some other point light sources are turned on.
If the configurations disclosed in JP-T-2003-534554, JP-A-2010-127671, and JP-A-2009-295318 are applied, two-dimensional coordinate data (for example, X coordinate data and Y coordinate data) of the target object can be obtained. In the case of using the optical position detection device as an input device or the like, there is a demand to limit the detection range in the Z-axis direction and set the detection range widely in the X-axis direction and the Y-axis direction. However, such settings are difficult to achieve in the configurations disclosed in JP-T-2003-534554, JP-A-2010-127671, and JP-A-2009-295318.